Project on Concrete Mix Design for various grades of Concrete
1. CONCRETE MIX DESIGN FOR M35 GRADE WITH FLY ASH:-
AIM & INTRODUCTION:-
To design a concrete mix for M35 grade with fly ash.
1) To achieve the designed/ desired workability in the plastic stage.
2) To achieve the desired minimum strength in the hardened stage.
3) To achieve the desired durability in the given environmental conditions.
4) To produce concrete as economically as possible, by replacing by fly ash instead of cement.
The following code books are used for mix design
- IS 456-2000 (Plain and reinforeced concrete code practice)
- IS 10262 - 2009 (Concrete mix proportioning - Guidelines)
- IS 10262 -2019 (Concrete mix proportioning - Guidelines)
- IS 383 -2016 (Coarse aggregate and Fine aggregate Specification)
- IS 9103-1999 (Concrete admixtures Specification)
- IS 1489-2015 Part 1&2 (Cementitious materials specification)
STEP BY STEP PROCEDURE TO DESIGN CONCRETE MIX M35 GRADE CONCRETE WITH FLY ASH:-
- Stipulations for proportioning: -
Grade of concrete - M35
Type of cement - OPC 43 grade Conforming to IS 8112
Maximum size of aggregate - 20MM
Minimum cement content - 320 kg/m3
Workability in terms of slump - 75mm (Pump able concrete)
Exposure condition - Severe
Method of placing concrete - Pumping
Degree of supervision - Good
Type of aggregate - Crushed angular aggregate
Maximum cement content - 450 kg/m3
Admixture used - superplasticizer
- Test date for materials: -
Cement used OPC 43 grade conforming to IS 8112
Specific gravity of cement - 3.15
Chemical admixture - superplasticizer conforming to IS 9103
Specific gravity of CA-2.74, FA-2.74
Water absorption of CA-0.5%, FA-1.0%
Free moisture of CA- Nil, FA- Nil
Sieve analysis
- Coarse aggregate - Table -02 of IS 383
Fine Aggregate - Conforming of grading Zone-2 of table-4 of IS 383
- Target mean compressive strength: -
Target mean strength of concrete f'ck = Fck + 1.65 S (S value IS 10262-2019 Table-2)
= 35 + (1.65 * 5)
= 43.25 N/mm2
- Selection of water cement ratio: -
Step-01
From the Graph
Hence water-cement ratio – 0.38
Step-02
From the table-5 of IS 456-2000 for severe exposure maximum water cement ratio - 0.45
0.38 < 0.45 Hence ok
Hence we consider lower water cement ratio = 0.38
- Selection of water content: -
From the table -2 of IS 10262-2009, Maximum water content 20mm aggregate = 186 Lit (For 25mm to 50mm slump range)
Estimated water content for 75mm slump = 186 + (3/100) *186 = 186 + 5.58
= 192 Lit
As per superplasticizer is used the water content can be reduced up to 30% and above
We assumed as water content reduction 25% is achieved with superplasticizer
Hence the arrived water content = 192 * 0.75 = 144 Lit or kg
- Calculation of cement content: -
Water cement ratio = 0.38
Cement content = (144/0.38) = 380 kg/m3
For replacement of cementitious materials content so calculated may be increased by 10 percent
= 380 + [(10/100) +380]
= 380 + 38 = 418 kg/m3
Fly ash @ 30 present of total cementitious material = 418 * 0.3 = 125 kg/m3
Hence Cement conten = 418 – 125 = 293 kg/m3
From table -5 of IS 456 minimum cement content for severe condition = 320 kg/m3
418 kg/m3 > 320 kg/m3 Hence ok
So, revised Water cementitious ratio = 144/418 = 0.34
- Proportions of volume of coarse aggregate and Fine aggregate: -
From the table -3 of IS 10262 - 2019 volume of CA corresponding to 20mm size aggregate and FA (Zone-2) for W/C ratio 0.5 = 0.62
In the present case the water cement ratio is 0.34
Therefore, the volume of coarse aggregate needs to be increased to decrease the fine aggregate content
As water cement ratio is lower by o.10 the proportion of volume of CA is increased by 0.02 (at the rate of +/-0.01 for every +/- 0.05 change in water cement ratio)
Therefore, corrected volume of CA for the water cement ratio of 0.34 = {[(0.5-W/C)/0.0] * 0.01} + volume of CA = 0.652
(Note: - If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably based on experience
for pump able concrete these values are reduced by 10%
Therefore, volume of CA =0.652 * 0.9 = 0.59
Volume of FA content = 1-0.59 = 0.41
Chemical admixture: -
Volume of chemical admixture (superplasticizer) @ 2% by mass of cementitious material
= (2/100) * 418
= 8.4 Kg/m3
- Mix calculation: -
The mix calculation per unit volume of concrete shall be as follows: -
- Volume of concrete = 1 m3
- Volume of cement = (293/3.15) *(1/1000) = 0.093 m3
- Volume of fly ash = (125/2.2) * (1/1000) = 0.056 M3
- Volume of water = (144/1) * (1/1000) = 0.14 m3
- Volume of chemical admixture = (8.4/1.145) *(1/1000) = 0.007 m3
- volume of aggregate CA & FA = a-(b +c + d + e) = 1-(0.093+0.056+0.14+0.007) = 0.704 m3
- Mass of CA = e * (volume of CA * Specific gravity of CA *1000) = 0.7 * 0.59 * 2.74 * 1000 = 1132 kg/m3
- Mass of FA = e * (volume of CA * Specific gravity of CA *1000) = 0.7 * 0.41 * 2.74 * 1000 = 786 Kg/m3
9.Mix proportions for trail mix: - 01
Cement - 293 kg/m3
Fly ash – 125 kg/m3
Water - 144 Lit/m3
Fine aggregate - 786 kg/m3
Coarse aggregate - 1132 kg/m3
Chemical admixture -8.4 kg/m3
water cement ratio - 0.34
1 : 2.68 : 3.86
10.Adjustment on water, FA and CA (If the CA and FA is in dry condition): -
1.Fine aggregate = Mass of FA in SSD condition/ {(1+Water absorption/100)}
= 786/ {1+(1/100)}
= 778 kg/m3
2.Coarse aggregate = Mass of CA in SSD condition/ {(1+Water absorption/100)}
= 1132/ {1+(0.5/100)}
= 1126 kg/m3
Extra water to be added for absorption by CA & FA: -
- For CA = Mass of Ca in SSD condition – Mass of CA in Dry conditions
= 1132 – 1126 = 6 kg
- For FA = 786 – 778 = 8 kg
The estimated requirement for added water, therefore
= 144 + 6 + 8
= 158 Kg/m3
11. Mix proportions for trail mix: - 02 (After adjustment for dry aggregate)
Cement - 293 kg/m3
Fly ash – 125 kg/m3
Water - 158 Lit/m3
Fine aggregate - 778 kg/m3
Coarse aggregate - 1126 kg/m3
Chemical admixture -8.4 kg/m3
water cement ratio - 0.34
1 : 2.65 : 3.84
12. Result:-
Thus the concrete mix is designed for M35 grade concrete with fly ash by following the above procedure. Two types of mix proportitons are arrived one with dry aggregates without considering water absorption and other by considering water absorption.
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportions shall be reworked for the actual water content and checked for durability requirements
2. CONCRETE MIX DESIGN FOR M50 GRADE WITHOUT FLY ASH:-
AIM & INTRODUCTION:-
To design a concrete mix for M50 grade without fly ash.
The object of mix design is to decide the proportions of materials which will produce concrete of required properties. The mix proportions should be selected in such a way that the resulting concrete is of desired workability while fresh and it could be placed and compacted easily for the intended purpose. The following code books are used for mix design
- IS 456-2000 (Plain and reinforeced concrete code practice)
- IS 10262 - 2009 (Concrete mix proportioning - Guidelines)
- IS 10262 -2019 (Concrete mix proportioning - Guidelines)
- IS 383 -2016 (Coarse aggregate and Fine aggregate Specification)
- IS 9103-1999 (Concrete admixtures Specification)
1. Stipulations for proportioning:-
Grade of concrete - M50
Type of cement - OPC 53 grade Conforming to IS 8112
Maximum size of aggregate - 20MM
Minimumum cement content - 320 kg/m3
Workability in terms of slump - 75mm
Eposure condition - Severe
Method of placing concrete - Pumping
Degree of supervision - Good
Type of aggregate - Crushed angular aggregate
Maximum cement content - 450 kg/m3
Admixture used - superplasticizer
2. Test date for materials:-
Cement used OPC 53 grade conforming to IS 8112
Specific gravity of cement - 3.2
Chemical admixture - superplasticizer conforming to IS 9103
Specific gravity of CA-2.7, FA-2.7
Water absorption of CA-0.5%, FA-1.0%
Free moisture of CA- Nil, FA- Nil
Sieve analysis
1. Coarse aggregate - Table -02 of IS 383
Fine Aggregate - Conforming of grading Zone-1 of table-4 of IS 383
3. Target mean compressive strenth:-
Target mean strength of concrete f'ck = Fck + 1.65 S
= 50 + (1.65 * 5)
= 58.25 N/mm2
4. Selection of water cement ratio:-
Step-01 - Calculation of W/C ratio from Graph as per IS 10262-2019
Hence we assume W/C = 0.34
Step-02
From the table-5 of IS 456-2000 for severe exposure maximum water cement ratio - 0.45
Lower water cement ratio is to be consierded as 0.34
0.34 < 0.45 Hence ok
5. Selection of water content:-
From the table -4 of IS 10262-2019, Maximum water content 20mm aggregate = 186 Lit (For 25mm to 50mm slump range)
Estimated water content for 75mm slump = 186 + (3/100)*186 = 186 + 5.58
= 191.6 Lit
As per superplasticizer is used thre water content can be reduced up to 30% and above
Based on the trails water content reduction 25% is achieved with plasticizer
Hence the arrived water content = 191.6 * 0.75 = 144 Lit
7. Calculation of cement content:-
Water cement ratio = 0.34
Cement content = (143.7/0.34) = 423 kg/m3
From table -5 of IS 456-2000 minimum cement content for severe condition = 320 kg/m3
423 kg/m3 > 320 kg/m3 Hence ok
8. Proportions of volume of coarse aggregate and Fine aggregate:-
From the table -5 of IS 10262 - 2019 volume of CA corresponding to 20mm size aggregate and FA (Zone-1) for W/C ratio 0.5 =0.6
In the present case the water cement ratio is 0.34
Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content
As water cement ratio is lower by 0.16 the proportion of volume of CA is increased by 0.03 (at the rate of +/-0.01 for every +/- 0.05 change in water cement ratio)
Therefore corrected volume of CA for the water cement ratio of 0.34 = 0.632
(Note:- If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably based on experience
for pumbable concrete these values are reduced by 10%
Therefore volume of CA =0.632 * 0.9 = 0.57
Volume of FA content = 1-0.57 = 0.43
8. Mix calculation:-
The mix calculation per unit volume of concrete shall be as follows:-
- Volume of concrete = 1 m3
- Volume of cement = (423/3.2)*(1/1000) = 132.19*0.001 = 0.132 m3
- Volume of water = (144/1)* (1/1000) = 0.144 m3
- Volume of chemical admixture = (8.46/1.145)*(1/1000) = 0.007 m3
- volume of aggregate CA & FA = a-(b+c+d) = 1-(0.132+0.144+0.007) = 1-0.2827 = 0.717 m3
- Mass of CA = e * (volume of CA * Specific gravity of CA *1000) = 0.717 * 0.57 * 2.7 * 1000 = 1103 kg/m3
- Mass of FA = e * (volume of FA * Specific gravity of CA *1000) = 0.717 * 0.43 * 2.7 * 1000 = 832 Kg/m3
9. Mix proportions for trail mix-01:-
Cement - 423 kg/m3
Water - 144 Lit/m3
Fine aggregate - 832 kg/m3
Coarse aggregate - 1103 kg/m3
Chemical admixture -8.46 kg/m3
water cement ratio - 0.34
1 : 1.97 : 2.61
10.Adjustment on water, FA and CA (If the CA and FA is in dry condition): -
1. Fine aggregate = Mass of FA in SSD condition/ {(1+Water absorption/100)}
= 832/ {1+(1/100)}
= 824 kg/m3
2. Coarse aggregate = Mass of CA in SSD condition/ {(1+Water absorption/100)}
= 1103/ {1+(0.5/100)}
= 1098 kg/m3
Extra water to be added for absorption by CA & FA: -
- For CA = Mass of Ca in SSD condition – Mass of CA in Dry conditions
= 1103 – 1098 = 5 kg
- For FA = 832 – 824 = 8 kg
The estimated requirement for added water, therefore
= 144 + 5 + 8
= 157 Kg/m3
11. Mix proportions for trail mix-02:- (After adjustment for dry aggregate)
Cement - 423 kg/m3
Water - 157 Lit/m3
Fine aggregate - 824 kg/m3
Coarse aggregate - 1098 kg/m3
Chemical admixture -8.46 kg/m3
water cement ratio - 0.34
1 : 1.94 : 2.59
12. Result:-
Thus the concrete mix is designed for M50 grade concrete by following the above procedure. Two types of mix proportitons are arrived one with dry aggregates without considering water absorption and other by considering water absorption.
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial, if required. The mix proportions shall be reworked for the actual water content and checked for durability requirements